As the Rev0verDrive said instead (together) of RPC it is better to use RepNotify variable. In this case, the structure will contain a reference to the actor to which you need to attach, and the binding coordinates.
This way you can set up the binding correctly if a player joins after you pick up the item.
However, if we add the ability for the client to take an item based on client data, then a client RPC to unbind is still necessary. Otherwise, it will cause visual bugs.
They will be corrected the moment the player tries to take another item.
It seems to me that it would be worthwhile to make a universal component that would manage actor replication and attachment.